Rotary hydraulic pump and pressure control valving therefor



Jan-`25, 1944. G. M. MAGRUM ET AL l 2,340,196

ROTARY HYDRAULIC PUMP AND PRESSURE CONTROL VALUING THEREFOB w n l A l dZnz/E'rzzr" E 0o @germs-e ff. Maeva, gl Mge? @ws/MAM, de.

Jan. 25, 1944. Q M MAGRUM ET AL l 2,340,196

ROTARY HYDRAULIC PUMP AND PRESSURE CONTROL VALVING THEREFOR Fiied June16, 1941 2 Sheets-.Sheet 2 .ZES-

lPatented Jan. 25, 1944 ROTARY HYDRAULIC PUMP AND PRESSUR CGNTROLVALVING THEREFOR Gervase M. Magrum and Harry L. Chisholm, Jr., Buialo,N. Y., assignors, by mesne assignments, to Houdaille-HersheyCorporation, Detroit, Mich., a corporation of Michigan Application .rune1e, 1941, serial No; 398,246

13 claims.. (ci. 10s-42) This invention relates to rotary hydraulicpumps and particularly to valving assembly forming part' of the pumpstructure for controlling the pump pressure.

The important' object of the invention is to provide compact valvlngassembly subjected to the pressure of the fluid pumped by the pump andfunctioning for relieving the pressure should the pump pressuregradually rise above normal predetermined pressure, and to provideblow-off for quick return to normal of the pressure should the pressuresuddenly rise abnormally, the pump being'thus protected againstoverloading automatically and holding the pump pressure within itspredetermined limits.

compressing packing around the shaft to pre-v vent leakage.v

The pump cylinder forming elements are rings and plates clamped togetherbetween the head I2 and the block I3 by a clamping ring 2 havingthreaded engagement in the open end ol the housing .wall I 0 andabutting the ange 22 lon I the head I2. As shown there are two rings 23Another important feature of the invention is Figure 3 is an elevationof the left end of the' pump structure.

The pump structure shown is of the welllmown type as, for` example, thatshown in the pending application of Sherwood C. Bliss, Serial No.282,447, led July 1, 1939, issued into Patent No. 2,271,730, datedFebruary'3, 1942.

Briefly describing the pump, its housing comprises the cylindrical wallIll having the inner end wall or head II integral therewith, the outerend of the housing receiving the outer 'end wall or head I2. Fittinginto the wall 'III and seating against the head II is the cylindricalblock I3 the various elements which form the pump cylinders. A driveshaft I4 extends into the housing and. is journaled in ball'bearings I5and 'I3 supported respectively by the block I3 and the head I2, theshaft .extending outwardly from the head II for mounting, or connectionwith, a

driving source (not shown) such as an electric motor. A fitting I'Ireceives .the shaft and is se cured, as by bolts I8, to the head II, andmay serve as a bracket for supporting the pump struc= ture. The tting I1engages a Washer I9 for and 24 respectively, an inner plate 25, anintermediate plate 26, and an outer plate 21, the outer diameters of therings and plates being such that they will iit snugly in the cylindricalbore of the wall I0. The rings and plates denne annular cylinder. spaces28 and 29 into whichd'lheA rotor members 30 and 3| respectively extendto be rotated by the shaft I4 to which they are secured as by keys 32.

vReferring to Figure 2, the rotor elements 30 1 and 3l are of generallyelliptical shape so as to y between which and the outer head I2 areclamped dene with the cylinder lspace walls crescent shaped workingchambers. The two .rotors are displaced ninety degrees from the shaft I4so that the opposite working chambers 33 and 34 between the rotor 30 andthe ring 23 will be displaced respectively ninety degrees from theWorking chambers 35 and 36 between the rotor 3| and the ring 24.

The. block I3`is cored out to provide a suction or intake space S and adischarge space D, the suction space S communicating with the inlet 3l!on the wall I!) connected by suitable piping with a source of uld suchas oil, and the discharge space or chamber D communicating with theoutlet 38 lon the wall I0 connectable by suitable piping with hydraulicdevices for receiving the huid under 'pressure from the pump.

For the cylinder spaces 28 and 29 in whichthe rotors. operate, i'luidinlet and uid outlet ports are provided. As vshown on vFigure 2, eachcylinder space has diametrically opposite inlet ports 39 and 39' anddiametrically opposite discharge ports 40 and 40. As shown on Figure 1,the rings 23 and 24 have transverse bores 4I therethrough which alignwiththe transverse bores 42 in the plates 25, 26 and 27 to form anoutlet passageway which at its inner end communicates with the dischargespace D connected with the outlet 38. The ports 40 extend through thevrings 23 and 2 4 to connect the pump chambers with the dischargepassageway through the rings and plates. At a diametrically oppositepoint, the rings and plates are bored to form another passagewaytherethrough connecting with the discharge space D andconnected by theports 40' with the pump chambers.A On Figure 2 the twoysthroughi-,heringendpiete assemblies are dicated by. d and d'.

The rings and plates are alsobored to provide `diametrically oppositeinlet passageways s and s communicating with the suction or inlet spaceS and connected by the ports 39 and 39' with the pump chambers- The.rings 23 and 24 are each provided with diametrically opposite blades 43and 43' for cooperating with the rotors surrounded by the respectiveVrings, the blades operating in radially extending slots u, the blades 43being located a collar 46 on the stem and the'top of the plug 46,

the springs tending to hold the blades with its edge in engagement withthe respective rotors. When'the pump is being driven the iluid will bedrawn into the space S from a source of supplysuch as a reservoir, theiluid being drawn by the rotors through the inlet passageways s and s'-an`d thrpughthe ports 38 and 39' into the working chambers 33, 34 and35, 36 and the blades will -intercept the fluid and direct it from theworking chambers into the outlet passageways d and d' and into thedischarge space D for outflow from the outlet 38 of the pump.

Describing now the valving structure for controlling the pump pressure,the valving assembly is located within the extension 49 from the pump.head I2. 'I'ne extension has the outer bore 56,'

and the inner bore 5I of larger diameter forming a chamber whose innerend ls closed by a plate 52 engaging between the ball bearing I6 and theshoulder 53 on the extension 43. The chamber 5I is connected with thebore 56 by na passageway 54 which is surrounded by an annular Valve seat55. A distance outwardly from the valve seat 55 a guide member or plug56 is seated in the bore 56 and is rigidly held in thebore as by pressfit therein, orj other means. outwardly oi the plug 56, a plunger member51 is. axially shiftable in the 'bore 56 and has a stem 56 extendingthrough The plunger. 51 is held against rotary movement in the bore 56as by means of a stop pin 62' Passageways 1l and 1I' through the head I2connect this space 6I with the outlet ends of the ldischarge passagewaysd and d' of the pump so that the space 6I always contains fluid underpump pressure. e

When the plunger 51 is in its normal position with the valve end 66engaging against the seat 55, the plunger body is separated from theguide plug 56 by an annular space 12 which is in communication throughports 13 with the bore in the stem 58 inwardly of the abutment nut 69.The plunger body lhas the restricted oriiice 14 connecting the -space 12with the space 15 be- 43 to communicate with the chamber 5I. The

space 5I has an outlet passageway 18 therefrom through the head I2 tothe exterior of the pump,

and this passageway may be connected with the supply source or reservoirfor the pump.

In order to adjust the tension of the spring 16 against the check valve68, provision is made for rotation of the abutment nut 69 from theexterior of the pump. .As shown, an vadjusting pin 13 extends-through agland 86 on the cap 64 the spring 16 against the valve 68.

extending from the plug 56 into a recess 63`in the I plunger. The outerend-of thel bore 56 is closed by a detachable 'cap 64 having threadedengagement. with the extensionlae d between/this cap i and the plungeris a' spring" 5 which; tendait) hold the plunger in position i'orseatingngageyment of thevalve end A66 with the valve seat-55. Theplunger andits stemehas the bore 66 therethrough` andthe stem', adistance outwardly from the valve end 66, has the annular internalilange 61 forming a seat for a relief valve which may 4be in the form ofa ball 68 within the bore 66. The 1 bore 66 at its outer end is threadedfor reception fof the abutment plug or nut '.66 between which and the,valve 68 is interposed a spring 16 which tends to hold the valve to itsseat 61 to disconnect the vplunger bore 6 3 from the space 6I.

Describing now the operation and functioningof the valving assembly, thepressure of springs 65 and 16 is such that the valves 66 and 66 willremain closed so long as the pump operates at or below a predeterminedmaximum delivery pressure. Should the delivery demand on the pump becomeless than the capacity of the pump, the delivery pressure will rise, andwhen the pressure becomes higher than the-predetermined magnitude, thepressure lagainst the valve 68 will overcome the resistance 'of thespring 16 and fluid will ow fromthe passages 1| and 1li, past the valve68 into the bore of the plunger stem, and

lfrom there through ports 13 and into the space 12. From here it must owthrough the relatively small orice 14, and' into thespace 15,V

As the pump pressure rises above maximum,v

the valve 68 will`be lifted oft its seat, allowing iiuid to now intospace .12. vSince the size of the orice 14 is relatively smaller'thanthe opening afforded by the valve 68, pressure'will build up in thespace 12, causing the plunger structure with its v/alve end 60 to'belifted oil its seat 55, allowing the iiuid in excess of the demand topass back to the reservoir.`

When the valve 66 has opened sufficiently to handle the excess uid, thepressure will stabilize at the maximum, or set pressure, and the valve68 will partly close until the ilow p ast the valve 68 is the same asthe ilow through the or'iilce 1li, thus maintaining a constant amount ofiluid in Athe space 12, and holding the valve 'A 66 to the properopening. By the same process,

. When the pressure has dropped below mum, i. e .,when the demand isthesame 'or'.lesa

flcient restriction that it makes a dashpot of plunger structure suresurface thereon normally unexposed to the pump discharge pressure butexposed to the flow through said relief passageway when said passagewayis opened,- a valve for said relief passageway, means for holding saidvalve Iclosed against normal pump pressure but permitting opening ofsaid valve by abnormal pressure for relief fiow through said reliefpassageway and exposure of said blow-off valve pressure surface to theflow through said relief passageway, means restricting the flow throughsaid relief passageway, means tending to hold said blow-off valve closedbut yielding to the relief flow pressure against said blow-off valvepressure surface for 1. A Valving assembly for controlling the pressurein a rotary hydraulic pump to prevent over-` closed against normalpressure in said pressure chamber, excess pressure against said reliefvalve causing opening thereof for ow of fluid through said reliefpassageway and against said pressure surface on the blow-off valvewhereby said blowoff valve will be moved for opening of said blowoffpassageway. l

2. Valving assembly for controlling the pressure in a rotary hydraulicpump to prevent overloading, comprising a pressure chamber connected toreceive fluid from the pump under discharge pressure, a blow-01Tpassageway from said pressure chamber to the exterior thereof, ablow-off valve for closing said passageway, a relief passageway fromsaid pressure chamber to the exterior thereof, said blowoff `valvehaving a pres-y sure surface normally unexposed to the pump dischargepressure but exposed to the flow through said relief Apassageway whensaid passageway is open, `a valve for said relief passageway and meansyieldingly 'holding said valve closed against normal pump pressure,abnormal pump pressure opening said valve for ow through said reliefpassageway and against said pressure surface on the v'blow-off valve,yielding means tending to hold said blow-olf valve closed and permittingopening thereof under excess pressure ow through said relief passagewayfor opening of said blow-olf passageway.

3. A Valving assembly for controlling the pressure in a rotary hydraulicpump to prevent overloading, comprising a pressure chamber connected toreceive fluid from the pump under discharge pressure, a blow-olfpassageway from said pressure chamber to the exterior thereof, ablow-off valve for closing said passageway, a relief passageway fromsaid pressure chamber to the exterior thereof, said blow-0E valve havinga presopening of said blow-off passage by said blow-off valve when thepump pressure becomes excessive.

4. Valving assembly for controlling the pressure in a rotary hydraulicpump to prevent overloading, comprising a valve chamber connected toreceive fluid from the pump at discharge pressure, a blow-off passagewayfrom said valve chamber to the `exterior thereof, a blow-off valve forclosing said passageway, a relief passageway from said valve chamber tothe exterior thereof, said blow-off valve having a pressure surfacenormally unexposed to the pump discharge pressure and exposed to theflow through said relief passageway only when said passageway is open,'avalve for said relief passageway vand yielding means normally holding itclosed against normal pump pressure, said valve opening under abnormalpump pressure for relief flow through said relief passageway andexposure of said blow-off valve pressure surface to said relief flowpressure, yielding means tending to hold said blow-off valve y closedAagainst said relief flow pressure,`a restricting orifice included insaid relief flow passageway for relieving said pressure against saidblowoff valve pressure surface sufliciently to prevent opening of saidblow-off valve by said pressure against said yielding means but beinginsufficient to sufllciently relieve 'the pressure under excess pumppressure whereby said blow-off valve will then be opened for pumppressure relief through v a valve for said reliefI passageway andyielding means normally holding it closed against'normal pump pressure,`said valve opening under abnormal pump pressure for relief ow throughsaid relief passageway and exposure of said blow-olf valve pressuresurface to said relief flow pressure, yielding means tending to holdsaid blowpressure againstfsaid blow-off valve to prevent opening thereofunder ordinary abnormal pump pressure but being insucienttorelieve thepres' sure sufficiently under excess pump pressure whereby said.blow-off valve will then rbe 'opened by the pressure against saidyielding means 'forg opening Aof the blow-01T passageway and relief ofthe excess pressure.

' `thereof for relief of ordinary abnormal pump pressure, a blow-oilvalve in said valve chamber for closing said blow-off passageway, arelief valve fbr controlling the flow through said relief passageway.yielding means holding said relief valve closed against normal pumppressure but permitting opening thereof for flow through said reliefpassageway under ordinary abnormal pump pres.- sure, means restrictingthe flow through said relief passageway whereby relief through saidpassageway will be gradual, yielding means tending to hold said blow-olfvalve closed, said blow-off valve having a pressure surface normallyunexposed to the pump discharge pressure and exposed to the flow throughsaid relief passageway charge pressure, ablow-off passageway from theinner end of said valve chamber to the exterior thereof, a blow-offvalve movable insaid guide member and yielding means normally holdingsaid valve to close said blow-oil' passageway, a plunger head on saidblow-off valve movable in the outer end of said valve chamber andnormally unexposed to the pump discharge pressure, a valve chamber insaid blow-oil valve, a relief passageway from the inner end of saidvalve chamber to the exterior thereofand including the valve chamber insaid blow-off valve, a relief valve in the valve chamber of saidblow-olf valve for said relief passageway, yielding means normallyholding said. relief valve closed against normal pump pressure butpermitting'opening thereby of said relief passageway under abnormal pumppressure, the inner side of said plunger head being exposed to the flowthrough said reliefpassageway only when said passageway is opened,whereby' under excess abnormal pump pressure said relief valve willfirst be opened for flow through said relief passageway and said blowoffvalve will then be opened by the excess pressure for opening of theblow-off passageway.

8. A valving assembly foi-controlling the pressure in a rotary hydraulicpump to prevent overf, loading, comprising a valve chamber in the pumpframe, a valve guiding member secured in said valve chamber intermediateits ends, the inner end of said valve chamber ybeing connected with thepump to receive fluid therefrom under discharge pressure, a blow-offpassageway fromthe inner l end of said valve chamber to the exteriorthereof,

a blow-ofi' valve movable in said guide member and yielding meansnormally holding said valve to close' said blow-off passageway, aplunger head for said blow-olf valve movable in the outer end of saidvalve chamber and normally unexposed to the pump discharge pressure, avalve chamber J in said blowon valve, a relief passageway from only when-said passageway is opened Iby said the inner end of said valvechamber-to the exterior thereof and including the valve chamber in saidblow-on valve, a relief valve in the valve chamber of said blow-offvalve for said relief passageway, yielding means holding said reliefvalve closed against normal pump pressure but permitting opening therebyof said relief passageway under abnormal pump pressure, the 'inner sideof said plunger head being exposed to the flow through said'reliefpassageway only when said passageway is open, whereby under excessabnormal pump pressure said relief valve will' mst be opened for ilowthrough said reliefpassageway and saidv blow-oil valve will then beopened by the excess pressure for opening of said blow-off passageway,lsaid plunger head having a restricted passageway therethrough includedin the fiowthrough said relief passageway .for retarding the closuremovement of said blow-oi! valve by its yielding means after relief of.the excess Pump pressure through said blow-off passageway.

9. A valving assembly for controlling the pressure in a rotaryAhydraulic pump kto prevent overloading thereof, comprising a pressurechamber connected to receive uid from thepump under discharge pressure,a blow-oil passageway from said pressure chamber vto the exteriorthereof, a blow-oir valve in said valve chamber and means normallyreleasably holding it for closurel of said blow-off passageway, saidblow-off valve having.

a pressure surface normally unexposed to the discharge pressure yin saidvalve chamber, a second passageway for conducting fluid flow underdischarge pressure from said pressure chamber against said blow-offvalve surface, a valve for said second passageway and means normallyyieldably holding it to close said second passageway against dischargenow under normal pressure, excess discharge pressure against said valveA sageway, said blow-off valve having a pressure surface thereonnormally -unexposed to the discharge Pressure in saidpressure chamber, apassageway through said blow-off valve for the iiow of fluidunderdischarge pressure to said pressure surface, a valve for saidpassageway in the blowoil valve and means normally yieldably holdingsaid valve closed against normal pressure in said pressure chamber,excess pressure against said valve in said passageway -in the blow-offvalve structure causing the opening thereof for-flow of uid underdischarge pressure against said pressure surface of the blow-oil' valvewhereby said blow-oi! valve will then'be moyed for opening of saidblow-oil' passageway.

11. A valving assembly for a rotary hydraulic pump for holding deliveressur determinedmaximum, ry p e below s' pre chamber connected with umtherefrom under the D D to receive fluid discharge pressure, a blow-oilcomprising a pressure passageway from said valve chamber to the exteriorof the pump, a blow-ofi valve movable in said pressure chamber andyielding means normally holding it for closure of said blow-oirpassageway, a second passageway from said pressure chamber to theexterior of the pump, said blowott valve having a pressure surfacethereon adapted to be exposed only to fiowthrough said sec- Y ondarypassageway, and a, check valve normally closing said second passagewayagainst vilow to said pressure surface but subjected to tlre pressure insaid pressure chamber to open said 'second passageway for flowtherethrough against said surface when the pump discharge pressure risesabove the predetermined'maximum thereby causing opening movement of saidblow-oil valve for opening of said blow-off passageway. v

12. A valving assembly for a rotary hydraulic pump for holding thedelivery pressure below a predetermined maximum, comprising a pressurechamber connected with the pump to receive iiuid therefrom underdischarge pressure, a blow-o passageway from said pressure chamber tothe exterior of the pump, a blow-off valve movable in said pressurechamber and yielding means normally holding it for closure of saidblow-01T passageway, a'. valve chamber within said blow-olf valve, asecond passageway from said pressure chamber to the exterior of the pumpand including said valve chamber, said blow-oi! valve having a pressuresurface thereon exposed only to iiow through said second passageway; aspring pressed check valve in said valvechamber normally closing saidsecond passageway against ow .l to said pressure surface but subjectedto the pressure in said pressure chamber to open said second passagewayfor iiow A therethrough against said sageway, a valve Ichamber withinsaid blow-oil' Y' so valve, a second passageway from said pressurechamber to the exterior of the pump and 'includ-' ing said valvechamber, said blow-oil valve having a pressuresurface thereon exposedonly to iiow through said second passageway, a spring pressed checkvalve in said valve chamber normally closing said second passagewayagainstiiow tc said pressure surface but subjected to the pressure insaid pressure chamber to open said second passageway for ow therethroughagainst' said surface when g the pump discharge pressure rises above apredetermined maximum thereby hausv ing movement of said blow-oil. valveto open said "blow-01T passageway for reduction of the pump dischargepressure below the predetermined maximum, and means in said secondpassageway for resistingthe iiow therethrough when 'said check valve isopen whereby to retard the opening movement of said blow-oir valve.

GERVASE M. MAGRUM.

HARRY L. CHISHOLM, Jn,

